A simple and efficient method for the production of stable, clear, high-potency oat extracts is disclosed. The method employs the use of differential dissociation constants and ultrafiltration to stabilise extracts, prevent hazing, and prevent the loss of functional activity as an anti-irritant and anti-oxidant. Also claimed are compositions of oat extracts derived from whole oat grains and oatmeal.
Further claims are made to compositions of oat extracts for use in cosmetic, nutraceutical, therapeutic medical and veterinary preparations.
The present invention relates to the production and use of solubilised, liquid oat extracts with formulations having utility in the personal care, cosmetics, nutraceutical, and pharmaceutical industries. More specifically the oat extract compositions of the present invention are useful as anti-irritants, anti-oxidants and skin-protection agents applied to the skin or when consumed.
Oats (Avena sativa), and especially colloidal oatmeal suspensions have been used historically as adjuncts to the treatment of atopic dermatitis. It is desirable to extract the active ingredients from the oat in order to facilitate the use of the grain in medicinal and cosmetic applications.
Oat derivatives such as colloidal oatmeal, hydrolysed oat protein, oat starch, and xcex2 glucan have been used in the cosmetics and pharmaceutical industries as a skin protectant which provides a smooth feel after use. Specifically, the carbohydrates and protein in the oat derivatives have been known to function as a protectant to aid in enhancing the skin""s barrier properties and thereby soothe the skin. Oat xcex2 glucans and lipids have also been known to function as emollients to lubricate and soothe the skin. For example, colloidal oatmeal has been used for bar soaps, bath powders, lotions, and poultices to treat skin that has been damaged, irritated, or distressed by a wide variety of causes. However, some oat derivatives, for example, colloidal oatmeal, are not fully soluble in aqueous solutions and leave undesirable residues on the skin and other surfaces. U.S. Pat. No. 5,219,340 describes a cloth applicator designed to retain colloidal oatmeal insoluble fractions.
Furthermore, hydrolysed oat protein undergoes processes such as hydrogenation, which may alter or adversely effect their properties. In particular, acid hydrolysed oat protein is known to have a strong odour which may adversely affect some consumer""s acceptance of the product.
Liquid oat extracts prepared by extraction with alcohol, glycols, ethers, esters, mixtures, and aqueous mixtures thereof are typically unstable materials, which if not emulsified, readily separate into oil and aqueous phases which may further separate into soluble and insoluble phases. The loss of materials from solution results in hazing and the loss of functional activity. Haze is irreversible and the extract cannot be clarified by heat, dilution, addition of surfactants, or solvents or pH. Attempts to clarify the extracts using filtration resulted in the loss of functional activity. The instability of oat extracts has limited utility in cosmetic and medical applications.
Paton (1995) Cosmetics and Toiletries 110:63 describes the cosmetic use of oat extracts and provides information on cosmetic formulations. The oat extract described, OSTAR ARRIVEEN(trademark), is produced from oats by a pearling process by which oat bran is obtained, which was then extracted with solvent. Charcoal was used in the process to clarify the preparation. The product is typically a dark brown coloured, non-homogeneous, bi-phasic extract. The utility of this product was limited by instability resulting in varying performance. The product could not be sterilised resulting in a high microbial load high due to non-kilned, non-stabilised oat bran.
Collins et al U.S. Pat. No. 5,169,660 describes the preparation of bran from cereal grains using aqueous alcohol extraction (83% w/w) and the recovery of crude by-products from waste through ion-exchange chromatography. The described process does not use pH pre-treatment or membrane filtration and so results in only recovered small quantities of by-product from waste. Utility is not described in cosmetic applications and pharmaceutical claims are not enabled. Collins on Oats: Chemistry and technology (1986) Ed. Webster AACC St. Paul, Minn. pp227-296 describes oat phenolic compound structure, occurrence and phytological function. Methods of extraction of these compounds and potential utility in the cosmetic and medical fields of use were not disclosed.
Onitsuka et al U.S. Pat. No. 5,716,605 describe the use of glycolic extracts of oats for the treatment and care of hair and the scalp. The extraction method described is different to the method of the present invention.
Cioca et al U.S. Pat. No. 5,552,135 describes improved sunscreen compositions including extracts from cereal plants. The primary extraction is made with chloroform or ethanol and further processed further in alcohol following evaporative concentration.
Hammonds et al PCF/US97/10724 describes fibrous sheet materials containing oat extracts to provide a soothing effect to the skin of the user. The oat extracts claimed are made by treating oats with extraction agents by methods known to those skilled in the art. Methods of preparing oat extracts are not disclosed; the described product used specific concentrations of OSTAR ARRIVEEN(trademark) in the preferred mode.
Zimmerman U.S. Pat. No. 5,888,521 describes compositions for topical use consisting of hydroxycarboxylic acid and oat extract, and also relates to methods of enhancing the rate of skin desquamation. Methods of preparing oat extracts are not disclosed; the described product used specific concentrations of OSTAR ARRIVEEN(trademark) in the preferred mode.
Roger et al U.S. Pat. No. 5,026,548 describes a phospholipid surfactant for use as a viscosity reducing agent in chocolate, or an emulsifier, surfactant or foam stabilizer in the food and other industries is produced by extracting oats using an alcohol such as ethanol or propanol, extracting the alcohol extract with methanol and evaporating the methanol.
Targan U.S. Pat. No. 5,468,491 describes a method for producing an aqueous oat syrup involving enzymatic digestion, cooking, filtration through on oat bed, and concentration to produce an extract composed of 80% sugars and 20% water. Utility is expressed as a flavour, colour, sweetener, and or texture enhancer. The composition is different to the present liquid oat extract.
Rouanet et al PCT/FR98/00826 describes a method for making a solid preparation of white colloidal oats, comprising the following steps: using cultivated oat seeds; stabilizing by at least one operation whereby dry vapour is injected followed by sudden cooling, preferably at about room temperature; pinning and drying; breaking and eliminating the bran; dimensional selecting of particles.
Vallet Mas et al EP 0 661 047 describes the combination of topical anti-histamines with solid oat flour to form an emulsion for the treatment of itching, reduction of inflammation and facilitation of spreading over the effected area. No reference is made to the anti-irritant potential of oat extracts,
Kovacs EP 0 282 002 describes the use of combinations of nettle (Urtica) and oat extracts as food additives or pharmaceutical preparations. The methods of preparing the oat extracts are described as, xe2x80x9cclassical methodsxe2x80x9d and no enabling details are provided.
Lawrence U.S. Pat. No. 5,573,785 describes an oat derived, skin conditioning, cosmetic component produced by dispersing in water a water-soluble fibre composed of about 4 to 6 weight percent beta glucan, about 1 to 5 weight percent fat, about 80 to 94 weight percent carbohydrates and less than 8 weight percent protein. No data relating to anti-irritant and redness reduction is provided. Furthermore, composition is radically different.
The commercial uses of ultra-filtration are known to those skilled in the art. Uses include water purification, milk processing, fruit juice, and wine clarification. However, ultra-filtration cannot be used for processing oat extracts without first stabilising the product by reducing pH. The high oil content of oats compounds this problem.
Reverse osmosis is known to those skilled in the art for the production of water from salt solutions. The use of reverse osmosis for the concentration of alcoholic extracts and solvent recovery as described in the present invention is novel.
1. Primarily, the present invention provides a method for the production of an oat extract that offers several advantages over the known methods of extraction and enhances the properties of the extract.
Histological staining of intact oat kernels indicated that the phenolic compounds were located primarily in the aleurone layer of the oat kernel. This implied that enriched preparations of the functional compounds would best be made from bran obtained by conventional milling or debranning processes. We were surprised to discover that the maximum yield of Avenanthramides came from the whole oat, not a bran fraction.
The present invention is based on the discoveries that (a) the extraction of active ingredients from oat may be enhanced in terms of production and efficiency, and furthermore (b) the resulting extracts are stable for extended shelf-life periods and may be concentrated readily.
Thus, according to a first aspect of the present invention there is disclosed a method for producing of an oat extract comprising the following steps:
a. Milling whole oats,
b. Extracting the resulting oatmeal with a solvent,
c. Adjusting the pH of the resulting oat extract to  less than 4.0 (favorably  less than 3.5),
d. Membrane filtration (e.g. ultra-filtration) of the oat extract through a membrane  less than 104 MWCO
The oat extract produced according to the method of the present invention is quantifiable in terms of activity and certified product quality assurance can be given. In accordance with the invention, aqueous alcoholic extracts of whole oats or groats are refined to provide materials for use in cosmetic and pharmaceutical compositions such as creams, gels, powders, lotions, and the like.
The oat extract of the present invention preferably contains Avenanthramide (as defined below) at a concentration of between 1 and 1500 ppm of Avenanthramide, more preferably between 3 and 450 ppm of Avenanthramide, and most preferably between 15 and 150 ppm of Avenanthramide. Other compounds, for example phenolics, benzoic and cinnamic acids, flavones, flavonols, chalcones, flavanones, proanthocyanidins, aminophenolics, tocols, and saponins, are also found in the oat extract. These compounds may have utility as for example, anti-oxidants, sunscreens, and surfactants.
The oat extract according to the present invention contains no or very little amounts of xcex2 glucan, for example less than about 0.01%, and less than 0.01% protein of molecular weight greater than 10,000 Da.
Preferably in step d of the method according to the present invention the membrane filtration is an ultra-filtration.
Preferably, reverse osmosis is used to further concentrate and purify the oat extract obtained by step d.
In step b die solvent for extracting the oatmeal favorably comprises water and a primary alcohol. The primary alcohol is preferably selected from the group consisting of ethanol, methanol, propanol (n-, iso-), butanol (n-, iso-, tert-), or mixtures thereof. Ethanol:water is preferred.
The oat extract may be incorporated into a solvent for ease of handling. For example in a preferred embodiment, the oat extract is incorporated in a 1:1 w/w mixture of 1,3 butylene glycol and water.
The oat extract obtained according to the method of the present invention can be easily sterilised by heat, microfiltration, or irradiation (after step c or d).
2. According to a second aspect the present invention relates to therapeutic (pharmaceutical) or cosmetic compositions, in particular for treatment of skin, which may be formulated as solution, gel, lotion, cream, ointment, or other acceptable form.
The composition favorably comprises Avenanthramide in a concentration of between 0.01 and 150 ppm., more preferably between 0.01 and 50 ppm, even more preferably between 0.3 and 15 ppm, and most preferably between 1.5 and 4.5 ppm.
Equally favorable is a therapeutic or cosmetic composition comprising between 0.1 and 25 weight percent, preferably 1 and 10 percent, of an oat extract comprising Avenathramide in a concentration of, referring to the oat extract, between 1 and 1500 ppm, preferably 3 and 450 ppm of Avenanthramide. The oat extract comprised in the composition is preferably produced according to the method of the present invention (see 1. above).
The composition according to the second aspect of the present invention may also contain various known and conventional therapeutic and/or cosmetic ingredients providing they do not detrimentally affect the desired reduction of skin irritation. For example, cosmetic ingredients such as alcohols, fats and oils, surfactants, fatty acids, silicones, humectants, moisturisers, viscosity modifiers, emulsifiers, stabilisers, colourings agents, and perfumes or fragrances may be included.
The composition can be used as a dermatological cosmetic product, in particular for use in the treatment of sensitive skin and/or redness (and/or wrinkles of the skin and/or pigment spots).
Typically, therapeutic or cosmetic compositions according to the present invention are topically applied to the skin.
3. A third aspect of the present invention relates to the use of an oat extract which comprises Avenanthramide, preferably an oat extract
(a) prepared according to the present invention and/or
(b) comprising Avenathramide in a concentration as stated above,
for the preparation of a topical dermatological therapeutic composition for treating erythema, pruritus, otitis, inflammations, irritations, and/or allergies affecting the skin,
for the preparation of a topical dermatological composition with enhanced therapeutic effect for use in the treatment of disorder of skin and/or for the treatment of inflammations, and
for the preparation of a topical dermatological composition with enhanced therapeutic effect for use in the treatment of disorder of skin and/or for the treatment of erythema, pruritus, otitis, inflammations, irritations, and/or allergies affecting the skin.
The use of the oat extract for the respective purposes corresponds to methods of imparting the respective therapeutic activity to a substance by adding a therapeutically effective amount of the oat extract
4. A fourth aspect of the present invention relates to Avenanthramide for use in the therapeutic treatment of disorder of skin and/or inflammations, This aspect corresponds to
(a) a method for therapeutic treatment of disorder of skin and/or inflammations, comprising applying a therapeutically effective amount of Avenanthramide to the skin, preferably in form of an oat extract and/or formulated in a suitable carrier,
(b) the substance(s) Avenanthramide for use in the therapeutic treatment of disorder of skin and/or inflammations, and
(c) a therapeutic composition, in particular for treatment of disorder of skin and/or inflammations, comprising a therapeutically effective amount of Avenanthramide.
Details of therapeutic treatment are given below.
5. A fifth aspect of the present invention relates to an oat extract containing a minimum of 10 ppm of Avenanthramide, wherein the oat extract can be produced by a method comprising steps a-d as above, and the additional step
e. Adjusting the concentration of Avenanthramide in the permeate after membrane filtration to  greater than 10 ppm